#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<string.h>
int main()
{
    char arr[1000] = { 0 };
    int i = 0;
    int j = 0;
    int n = 0;
    char val = 0;

    scanf("%s", arr);
    n = (int)strlen(arr);
    for (i = 0; i < n-1; i++)
    {
        for (j = 0; j < n - i-1; j++)
        {
            if (arr[j] > arr[j + 1])
            {
                val = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = val;
            }
        }
    }

    printf("%s", arr);
    return 0;
}